Electropneumatic brake apparatus



E. E. HEWITT ELECTROPNEUMATIC BRAKE APPARATUS Feb. 22, 1938.

Fied June 2 2 Sheets-Sheet l BY @ww ATTORNEY Feb. 22, 193s. Y E. E.HEwlTT 2,109,046

ELECTROPNEUMATIC BRAKE APPARATUS Filed June 2, 1937 2 sheets-sheet 2M3C@ INVENTOR ELLIS E W-IEWlTT `ATTOR NEY Patented Feb. 22, 193% NETES''S ELECTROPNEUMATIG BRAKE APPARATUS Application June 2, 1937, SerialNo. 145,976

16 Claims.

This invention relates to 'electro-pneumatic brake apparatus andparticularly to electropneumatic brake apparatus having signal equipmentfor signaling a fault, break or other failure 5- oi the electricalcircuits, and means for causing an automatic application of the brakesupon the failure ci the electrical circuits.

it is an object of this invention to provide an electro-pneumatic brakeapparatus including a l retardation controller for automaticallyregulating the degree of braking force so as to cause deceleration ofthe vehicle or train at a substantially constant rate and includingsignal equipment which functions at one time to indicate the l operativecondition of the retardation controller and at another time to indicatea fault or other failure in the electrical control circuits.

Another object of the invention is to provide an electro-pneumatic brakeapparatus of the 550 character indicated in the foregoing object andincluding normally closed brake control circuits having means responsiveto the interruption oi the control circuits to automatically eirect anapplication of the brakes, and including means for preventing anautomatic application of the brakes upon interruption of the controlcircuits due to the normal operation of the retardation controller.

The above objects, and other objects which will be made apparenthereinafter, are attained by sever-al embodiments of my inventionsubsequently to be described and shown in the accompanying drawings,wherein,

Fig. l is a diagrammatic View of an electropneumatic brake apparatus iora train of cars,

iilustrating one embodiment of my invention,

2 is a fragmentary diagrammatic View, ilustrating the operation of theretardation conroller shown in Fig. l,

Fig. 3 a fragmentary diagrammatic View, illustrating a modication oi theembodiment shown in Fig. l, and

Fig. i is a diagrammatic view of an electropneuma brake apparatus,illustrating another embodiment of my invention.

Description of embodiment shown in Figs. 1 and 2 lie train brakeequipment, shown in Fig. l, includes a brake pipe il which extendsthrough all the cars of the train, a brake valve device I2 of any vieilknown type used in automatic uid pressure brake systems for controllingthe charging the release of iluid under pressure from the pipe, aplurality of brake cylinders IS, i3d and i322I associated with wheeltrucks on different cars respectively, a plurality of auxiliaryreservoirs I4, Ida and Ilib on the different cars respectively, and aplurality of automatic valve devices I5, I5a and Iiib', illustrated astriple valves, which are controlled according to the variations ofpressure in the brake pipe EI for causing the charging of the auxiliaryreservoirs iro-m the brake pipe and the supply of iiuid under pressurefrom the auxiliary reservoirs I 4, 54a and Moto the brake cylinders I3,I3d and i319, respectively.

The equipment further includes a plurality of valve mechanisms I6, Italland lebv interposed, respectively, between each triple valve and thecorresponding brake cylinder and controlled by a retardation controlleril', located on one of the cars, through the medium of a plurality oftrain wires i3, le, 2S and 2I.

Operating on the brake control circuits, which include the train wires IS to 2l, are two relays 24 and "i5 which respectively control thecircuits for two signal lamps 26 and 2l.

A magnet valve device 29 controlled by either of the relays 2t or 25 inturn controls the operation of an application valve device 3| to eiectrapid reduction of the pressure in the brake pipe A cut-ofi valve device32, controlled by the pressure in the brake cylinder I3, is provided forpreventing the magnet valve device 29 from causing operation of theapplication valve device 3i. A timing reservoir 33 associated with theapplication valve device 3l functions to delay the operation of theapplication valve device 3l for a certain length of time upon operationof the magnet valve device 29.

The brake valve device l2 may be of any suitable type but, forsimplicity, it will be assumed to be or the simple rotary type having arotary valve, not shown, which is operated by an operating handle 35into a brake release position, a service application position, a lapposition and an emergency application position. With the rotary valve ofthe brake valve device i2 in brake release position, communication isestablished between a pipe 35 that is connected to a source of fluidpressure supp-ly, such as a main reservoir, not shown, and the brakepipe Il to charge the brake pipe to the normal pressure carried therein.With the rotary valve oi the brake valve device I2 in serviceapplication position, the connection from the pipe 38 to the brake pipeII is cut off or closed and communication established for reducing thepressure in the brake pipe ii at a service rate. In a similar manner,with CTI the rotary valve of the brake valve device i2 in emergencyapplication position, the connection between the pipe 55 and the brakepipe Il is closed and a communication is'establish-ed for reducing thepressure in the brake pipe II at an emergency rate. With the rotaryvalve of the brake valve device I2 in lap position, the connectionbetween the pipe 36 and the brake pipe ll is closedV and the exhaustcommunication effective in service or emergency application positions islapped or closed and the brake pipe II thereby isolated.

The automatic valve devices or triple valves i5, Ia and 55h are of wellknown construction and need no description herein except to point outthat they are operated upon a reduction in brake pipe pressure at aservice rate to supply fluid under pressure from the auxiliaryreservoirs i4, 14a and I4b to the brake cylinders I3, i3d and 23h,respectively, to effect service applications of the brakes on the train.Upon an increase in the pressure of the brake pipe II, the triple valvesI5, l5a and i519 are operated to establish communication through whichpressure is` released from the brake cylinders I3, I3a. and lh,respectively, and communication through which the auxiliary reservoirsI4, I 4a and i411 are charged with iluid under pressure from the brakepipe l I.

The magnet valve mechanisms I5, I6a and I6b are identical inconstruction and accordingly only the valve mechanism I5 is shown insection and described herein. The magnet valve mechanism i8 comprises acut-off magnet valve device 38, a release magnet valve device 39, aninshot valve device 4I, and a safety valve 42.

The cut-off magnet Valve device comprises a valve 43, hereinafter calledthe cut-off valve, which is contained in a chamber 44 constantlyconnected to the usual brake cylinder port of the triple Valve I5through a passage and pipe 5, and an electromagnet 46 for operating thevalve 43. When energized, the electromagnet 46 actuates a plunger orstem 41 to unseat the cutoif valve 43 against the resistance of abiasing spring 48 contained in the chamber 44. When the cut-off valve 43is unseated it establishes communication therepast from the chamber 44to a chamber 49, which is connected through a passage 5I to a chamber 52and, from the chamber 52, through a pipe 53 to the brake cylinder I3.When the electromagnet 48 is deenergized, spring 48 urges the valve 43into seated relation on an associated valve seat to cut offcommunication between the chamber 44 and the chamber 49.

The release magnet valve 38 comprises a valve 5E, hereinafter called therelease valve, and an electromagnet 5i for operating the valve 56. Thevalve 55 is contained in a` chamber 58 which is connected through a pipe58 to the safety valve 42.

When the electromagnet 51 is energized, it actuates a plunger or stem 5Ito shift the release valve 55 into seated engagement on an associatedvalve seat against the force of a biasing spring S2 contained in chamber52. When the electromagnet 5l is deenergized, the spring 62 unseats therelease valve 55 and communication is thereby established past therelease valve from the chamber 52 and the connected brake cylinder I3 tothe chamber 58 and the connected safety valve 42. As will be hereinafterexplained, the safety valve 42 is set so as to permit release of fluidVUnder pressure Vtherethrough from the brake cylinder to atmosphere onlywhen the pressure exceeds a certain predetermined pressure.

The inshot valve device 4I comprises a ball check valve 55, that iscontained in a chamber 86 connected to the chamber 44 through a passage6I, and a piston 68 having at one side a stem BS and yieldingly urgedupwardly into engagement with an annular rib seat II by a coil spring'I2 at the opposite side of the piston. When the piston 68 is in itsupper position shown, the stem 69 engages and unseats the ball checkvalve 65 to open communication between the chamber 66 and a passage 13leading to the chamber 49.

It will thus be seen that as long as the ball check valve 85 isunseated, uid under pressure may be supplied from the chamber 44 to thechamber 49 and to the brake cylinder I3 in parallel or by-pass relationto the cut-off valve 43 under the control of the triple valve device I5,notwithstanding the fact that the cut-off valve 43 may be seated.

The piston B8 is subject tobrake cylinder pressure on the side thereofopposite to the spring "I2, as will be apparent, and as long as thebrake cylinder pressure acting on the piston does not exceed a certainpressure, such as twenty or thirty pounds per square inch, the spring 12holds the piston 68 in its upper position to maintain the ball checkvalve 65 unseated. When the brake cylinder pressure exceeds the certainuniform pressure, the spring 'I2 yields and the piston 68 is urgeddownwardly into engagement with a gasket seat 75, whereby leakage offluid under pressure past the piston is prevented. When seated on thegasket seat 15, the piston 68 isV lowered so that the stem 69 thereof isretracted from the ball check valve 65. The ball check valve 85 nowseats to prevent the flow of fluid under pressure from the chamber 6B tothe passage 73 in by-pass relation to the cut-olf valve 43, but isadapted to unseat at any time to permit reverse flow of uid underpressure therepast.

The retardation controller device I'I may be of any suitable type, andis illustrated diagrammatically as comprising an inertia member in theform of a pendulum 8I which hangs in a vertical position as shown inFig. l as long as the vehicle or train is stopped or as long as thevehicle or train is traveling at a substantially constant rate of speed.The pendulum 8| carries, in insulated relation thereon, a contact member82 which is constantly connected as by a wire 83, including a flexibleportion 84, and by a branch wire 85 to one terminal of a battery 86hereinafter called the positive terminal. When the pendulum SI is in itsnormal Vertical position, the contact member 82 engages twospring-tensioned contact lingers 8I and 88 which are connected by wires88 and 9 I respectively, to corresponding terminals of theelectromagnets 46 and 5'I of the magnet valve devices 38 and 39 of themagnet valve mechanism IB.

Upon the retardation of the vehicle or train when traveling in a forwarddirection, the pendulum 8| shifts in the left-hand direction as viewedin Fig. 1, the contact fingers 8l and 88 being so disposed, as shown inFig. 2, that the contact member 82 at rst disengages only the contactfinger 87 and, subsequently, the contact nger 88. Y

The relay 24 is illustrated diagrammatically as comprising anelectromagnet 55 and a pair of contact members 96 and 91 which are urgedto a circuit-closing position when the electromagnet 85 is deenergizedand fwhich are actuated t0 a circuit-opening position when theelectromagnet 95 is energized. The relay 25 is identical to the relay 24and comprises an eleotrornagnet S8 and a pair of contact members 99 and|0|, which are urged to a circuit-closing position when theelectromagnet 98 is deenergized and which are actuated to acircuit-opening position when the electromagnet 98 is energized.

As is clearly apparent in Fig. 1, the contact members 95 and 99 of therelays 24 and 25, When in circuit-closing position, complete circuitsincluding the battery 85 and thus cause energizetion and consequentillumination of the signal lamps 26 and 21 respectively. The contactmembers 9'! or |0| of the relays 24 and 25, respectively, are eacheffective, when in circuit-closing posi* tion, to connect the positiveterminal of the battery 86 to a wire |03 which is connected to oneterminal of the electromagnet of the magnet valve device 29.

The magnet valve device 29 comprises a valve |05, which is contained ina chamber |06, and an electromagnet 01 which is effective When energizedto actuate a plunger |08 to unseat the valve |05 against the resistanceof a yielding spring |09. When the valve |05 is unseated, it establishescommunication from the chamber |05 to a chamber which is constantly opento atmosphere through an exhaust port ||2.

The application valve device 3| comprises a casing I4 containing a valvepiston ||6 which is normally yieldingly urged by a coil spring intoseated engagement on an annular rib seat i i to close communication froma chamber i9, which is constantly connected to the brake pipe by abranch pipe |2|, to a chamber |22 which is constantly open to atmospherethrough a large exhaust port |20. On the same side of the valve pistonH5 acted upon by the spring is a chamber |23 which is connected to thechamber ||9 through a restricted port |24 and to the timing reservoir 33through a pipe |25.

When the brake pipe is charged to its normal pressure, iiuid underpressure is supplied therefrom through the restricted port |24 to thechamber |23 and the combined force of the spring and the pressure of thefluid in` the chamber |23 is effective to maintain the valve piston H5seated on the annular rib seat ||8 against the opposing force of brakepipe pressure acting on the outer seated area of the valve piston |||iin the chamber HS. Upon a reduction of the pressure in the chamber |23,the rate of ow of fluid under pressure from the chamber ||9 to thechamber |23 is restricted by the port |24 and consequently the higherbrake pipe pressure acting on the outer seated area of the valve piston||6 shifts the valve piston HB upwardly against the resistance of thespring and unseats it from the annular rib seat H3 to estab lishcommunication from the chamber I9 to the atmospheric chamber |22,thereby causing a sudden reduction of the pressure in the brake pipe atan emergency rate.

When the pressure in the chambers i9 and |23 is subsequently equalized,the spring becomes effective to reseat the Valve piston and thus closethe connection from the chamber iii; to the atmospheric chamber |22.

The cut-off valve device 32 comprises a casing |25 containing adiaphragm type valve i2? which is suitably clamped in the casing andwhich is normally positioned to establish oommunicaticn through a port|28 between a chamber |29, which is connected to the chamber |65 of themagnet valve device 29 by a pipe |3I, and

a chamber |32 that is connected by the pipe |25 to the timing reservoir`33. Also suitably clamped in the casing |25 is a diaphragm |34 which iseffective, when subject to fluid under pressure in a chamber |35 at oneside thereof, to shift the diaphragm valve |27 into seated relation toclose communication between the chambers |29 and |32 through the port|23. The supply and release of fluid under pressure to and from thechamber |35 is under the control of a valve piston |36 which is normallyurged by a coil spring |3'| at one side thereof into seated relation onan associated valve seat to close communication through a port |38connecting the chamber |35 to a chamber |30 which is constantlyconnected to the brake cylinder through a branch pipe |4| of the brakecylinder pipe 53. The coil spring I3? is so designed and so adjusted intension as to maintain the valve piston |35 seated on its associatedvalve seat against the brake cylinder pressure acting in chamber on theinner seated area thereof, as long as the brake cylinder pressure doesnot exceed a certain uniform pressure, such as ten pounds per squareinch. When the brake cylinder pressure acting on the valve piston inchamber |39 increases sufiiciently to unseat the valve piston againstthe resistance of the spring |3l, the entire face of the piston becomessubject to the pressure in the brake cylinder and the valve piston isaccordingly suddently snapped upwardly into seated relation on a gasketseat |42 to close off the normal exhaust communication from the chamber|35 to atmosphere through eX- haust ports and passage |43. When thebrake cylinder pressure in the chambers |35 and |39 is ineffective tomaintain the valve piston |35 unseated against the force of the spring|31', the valve piston |36 is shifted downwardly to close the port |38and to open the communication through which fluid under pressure isvented to atmosphere from the chamber |35 through the exhaust ports andpassage |43.

It will be apparent that, with the diaphragm valve |2ll of the cut-ofivalve device 32 unseated, energization of the electromagnet |91 of themagnet valve device 29 is eifective to establish communication throughwhich the timing reservoir 33 and connected chamber |23 of theapplication valve device 3| are vented to atmosphere. The port ||2 andthe timing reservoir 33 provide a certain time delay, such as three orfour seconds, following the energization of the electromagnet |07 of themagnet valve device 25, before suicient pressure reduction is effectedin the chamber |23 of the application valve device 3| to causeuri-seating of the valve piston H5 and the consequent reduction in brakepipe pressure. Thus, momentary accidental deenergization of the magnetvalve device 29 does not ren sult in undesired operation of theapplication valve device 3|.

it will also be apparent that when the diaphragm valve |27 of thecut-off valve device 32 is seated to close the port |23, energization ofthe magnet valve device 29 is ineffective to cause operation of theapplication valve device 3|.

The circuits by which the retardation controller controls cnergisaticnand deenergizan tion of the magnet valve devices 32 and 39 of the magnetvalve mechanisms iii, ita and |51) as well as of the relays 24 and 25should be readily apparent. It will be seen that the electromagnets 45of magnet valve devices 38 are all connected in series relation in thetrain wire |8,

that the train Wire I8 is connected through a connector I 5I on the lastcar of the train to the train Wire I9, and that the electromagnet 95 ofthe relay 24 is connected in series relation in the train wire I9, Whichis in turn connected, as through a ground connection in the mannershown, to the negative or grounded terminal of the battery 86.

lt will be apparent also, that the electromagnets 5l of the magnet valvedevices 39 are connected in series relation in the train Wire 20, thatthe train` Wire 20 is connected through a connector 952 at the rear endof the train to the train wire 2l, which is in turn -connected asthrough a ground connection at the head end of the train in the mannershown, to the negative terminal of the battery 86, the electromagnet Q3of the relay 25 being connected in series relation in the train wire 2I.

With the pendulum 8| of the retardation controller in its normalvertical position, the control circuits just described are closed. Whenthe pendulum BI of the retardation controller Il shifts sufficiently inthe left-hand direction to cause the contact member 82 thereof todisengage the contact finger 81, the circuit for energizing relay 24 andthe magnet valve devices 33 is interrupted. When contact member 82 onthe pendulum El disengages contact finger 88, the circuit for energizingthe relay 25 and the magnet valve devices 39 is interrupted.

Operation of embodiment shown in Fig. 1

Let it be assumed that the brakeY pipe Ii is charged to a normalpressure by placing the operating handle 35 of the brake valve device I2in brake release position and that the triple valve devices i5, l5a andI5b are correspondingly conditioned to charge the auxiliary reservoirsi4, Ida and lh and establish the usual exhaust cornmunication wherebythe pipe 45 leading to the brake cylinders is connected to atmosphereand fluid under pressure correspondingly exhausted from the brakecylinders to effect release of the brakes. Let it be further assumedthat the vehicle or train is traveling along the road at a substantiallyconstant rate of speed so that the pendulum 6l of the retardationcontroller I'I is in its normal vertical position completing thecircuits just previously described for energizing the magnet valve-devices 38 and 39 of the magnet valve mechanisms I5, Ia and I6b andalso the electromagnets 95 and 98 of the relays 2li and 25,respectively.

The cut-off valves 43 are correspondingly unseated and the releaseValves 5S correspondingly seated so that the exhaust communication forreleasing :duid under pressure from the brake cylinders is establishedby Way of the pipe 53, chamber 52, passage 5I, chamber 49, past theunseated cut-oir valve 43, chamber 44, passage and pipe iii and throughthe triple valve to atmosphere. bers 96 and 99 of the relays 24 and 25are shifted to circuit-opening positiony and the signal lamps 243 and 2iare correspondingly extinguished. Also magnet valve device 29 isdeenergized and valve 95 thereof seated since contact members Si' andIBI of relays 24 and 25 are both in circuit-opening position.

Since the brake pipe II is charged, the timing reservoir 33 is alsocharged correspondingly with fluid under pressure by Way of the branchpipe 3l, restricted port I24 and chamber |23, so that At the same time,the contact memthe valve piston IIS of the application valve device 35is seated. Since the brake cylinder I3 is at atmospheric pressure, thevalve piston 136 of the cut-off valve device 32 is seated to close theport 38 and thus fluid under pressure is vented from the chamber I 35 toatmosphere by Way of the ports and passage |43. The diaphragm valve l 21is accordingly unseated and, although fluid under pressure is suppliedto chamber it of the magnet valve device 29 from the timing reservoir 33through the pipe I25, chamber I32 of the cut-ofi valve device 32, openport I 29, chamber I29, and pipe I3I, the seated valve I preventsexhaust of fluid to atmosphere through port II2.

Let it now be assumed that the operator effects a service application ofthe brakes by shifting the operating handle 35 of the brake valve deviceI 2 to a service application position. The pressure in the brake pipe IIaccordingly reduces at a service rate and the triple valve devices I5,I5a and I5b are correspondingly operated to establish communication inthe usual manner through which fluid under pressure is supplied from theauxiliary reservoirs I4, I4a and I4b, respectively, to the brakecylinders I3, I3a and i311, respectively. When the desired degree ofservice application has been attained the operator shifts the operatinghandle 35 to lap position thereby cutting off further reduction of thepressure in the brake pipe II and causing the triple valves I5, I5a andI 5b to respond in the usual manner and operate to a lap position to cutolf the further supply of uid under pressure from the auxiliaryreservoirs to the brake cylinders and maintain the pressure establishedin the brake cylinders.

When the pressure in the brake cylinder exceeds the pressure, forexample ten pounds per square inch, required to unseat the valve pistonI 36 of the cut-off valve device 32, brake cylinder pressure is admittedto the chamber 35 and by acting on the diaphragm |34 causes thediaphragm valve I2'I to be shifted into seated position to close theport I28.

Now let it be assumed that due to the service application of the brakeseffected in the manner just described, the train is retarded at such arate as to cause the pendulum 8l of the retardation controller I1 toshift in the left-hand irection sufficiently to disengage the contactnger 8l, which may occur at, for example, a rate of retardation of thetrain of three miles per hour per second. The disengagement of thecontact member S2 on the pendulum 8! from the contact finger 8iinterrupts the circuit for energizing the electromagnets du of themagnet valve devices 39 as Well as the electroma-gnet 95 of the relay2d. As a result, the cut-01T valves 43 of all the valve devices 33 areactuated to seated position and the contact members 95 and 91 of therelay 24 are shifted to circuit-closing position.

The contact member 93 of relay i, when in circuit-closing position,completes the circuit for energizing the signal lamp 2&3 which isaccordingly illuminated to indicate to the operator that the retardationcontroller l'I has operated to close the cut-off valves 43.

The contact member 91 of the relay 2li, when in circuit-closingposition, completes the circuit for energizing the electromagnet illl ofthe magnet valve device 29 and the valve |95 is accordlingly unseated.Due to the fact that the diaphragm valve I2? of the cut-off valve 32 isseated,

the only eifect of the unseating of the valve |05 of the magnet valve29, in this instance, is to release fluid under pressure from thechamber |29 of the cut-olf valve device 32 and chamber |06 of the magnetValve device 29 through the exhaust port ||2.

With the brake cylinder pressure remaining unchanged, the rate ofretardation of the train increases as the speed of the train decreasesdue to the increase in the coefficient of friction between the brakeshoes and the rim of the vehicle wheels. Thus, the pendulum 8| of theretardation controller I1 shifts to a further extent in the left-handdirection and disengages the contact finger 88 of the retardationcontroller at, for example, a rate of retardation of four miles per hourper second. The disengagement of the contact member 82 on the pendulum8| from the contact finger 88 interrupts the circuit for energizing theelectromagnet 51 of each release magnet valve device 39 and also theelectromagnet 93 of the relay 25. As a result, the release valves 56 areunseated and the pressure in the brake cylinders I3 reduced to apressure determined by the setting of safety valve i2 which pressure isonly a few pounds per square inc-h higher than the pressure required toeffect operation of the inshot valve device |53. Accordingly, if thepressure in the brake cylinder |3 is higher than the pressure setting ofthe safety valve 42, fluid under pressure is released from the brakecylinder, thereby effecting a reduction in the degree of the retardingforce on the train and a corresponding decrease in the rate ofretardation of the train.

Contact member 39 of relay 25 is shifted to circuit closing position asa result of the deenergi- Zation of the electromagnet 38 and completesthe circuit for energizing the signal lamp 21 which is accordinglyilluminated to indicate to the operator that the retardation controller|1 has operated to effect the release of iiuid under pressure from thebrake cylinder. The shifting of contact member i0! of relay 25 tocircuit-closing position as a result of deenergization of electromagnet98 is without elect, since it merely establishes a parallel circuitaround the contact member 91 of relay 2, which is already incircuitclosing position.

When the rate of retardation of the train decreases sufciently that thependulum 3| returns in a right-hand direction back toward its normalvertical position sufficiently to effect reengagement of the contactmember 82 thereon with the contact finger S8, the circuit for energizingthe electromagnet 51 of each release magnet valve device 39 and of theelectromagnet 98 of the relay 25 is again established. Accordingly, therelease valves 56 are re-seated and the contact members S9 and ll of therelay 25 actuated to circuit-opening position. Signal lamp 21 isconsequently extinguished, indicating to the operator that the releaseof uid under pressure from the brake cylinder has ceased.

It will thus be apparent that as long as the brake cylinder pressureexceeds a certain uniform low pressure as determined by the pressuresetting of the cut-off Valve device 32, the interruption of the controlcircuits for the cut-01T magnet valve devices 33 and release magnetvalve devices 39 as Well as the relays 2d and 25 under the control ofthe retardation controller |1 results merely in the normal controlexercised by the retardation controller, the signal lamps 28 and 21being illuminated to indicate the respectively corresponding operativeconditions of the retardation controller.

When the train comes to a complete stop, the pendulum 8| of theretardation controller l1 returns to its normal vertical position inwhich the contact member 82 engages both the contact iingers 81 and 88and the cut-olf magnet valve devices 38 and release magnet valve devices39 are correspondingly positioned as shown in Fig. 1. The operator may,therefore, by operation of the brake valve device l2 increase brakecylinder pressure to any desired degree to hold the trainagainstcreepage on a grade.

When it is desired to start the train, the operator may release thebrakes by shifting the operating handle 35 of the brake valve device I2to release position, thereby restoring the normal pressure in the brakepipe and causing operation of the triple'valve devices |5, |511. and|5b` in the usual manner to recharge the auxiliary reservoirs |13, laand lb and to release iiuid under pressure from the brake cylinders i3,V| 3a and |312. Now let it be assumed that while the train is travelingalong the road at a substantially constant speed, one of the train Wireor brake control circuits, for example the circuit including train wiresi8 and I9, fails due to breakage thereof or the occurrence of a groundor other fault thereon. The cut-off magnet valve devices 38 and therelay Q5 are accordingly deenergized in the same manner as if thecontact member 82 of the retardation controller had disengaged thecontact nger 81. Due to the deenergization of the electromagnet 4B ofeach cut-off valve device 38, the cutofi valve 43 is shifted to seatedposition to cut off communication therepast to the brake cylinder. Upondeenergization of the electromagnet 95 of the relay 24, the contactmembers 95 and 91 thereof are shifted to circuit-closing position toeffect the illumination. of the signal lamp 26 and energization of theelectromagnet |31 of the magnet valve device 29, respectively.

Since the brakes are released, and only atmospheric pressure acts inchamber |35 on the diaphragm |34 of the cut-off" valve device 32, thediaphragm valve |21 is unseated and thus the unseating of the valve |65of the magnet valve device 24, due to the energization of theelectromagnet |81, establishes communication through which fluid underpressure is exhausted from the volume reservoir 33 and chamber |23 ofthe application valve device 3|.

After a certain uniform time interval, therefore, determined by thecapacity of the volume reservoir 33 and the size of the port |2iof themagnet valve device 29, the pressure in the chamber |23 of theapplication valve device 3| is reduced and the valve piston H5 thereofaccordingly unseated in the manner previously describedto rapidly reducethe pressure in the brake pipe at an emergency rate.

Upon the reduction of the pressure in the brake pipe at an emergencyrate, the triple valve devices I5, |50', and |55 respond in the usualmanner to'rapidly supply fluid under pressure from the auxiliaryreservoirs |4, |4a and Mb, respectively, to the brake cylinders I3, |3aand |31) respectively, to effect an emergency application of the brakes.

In view of the fact that the cut-off Valves 43 are seated, however,iiuid under pressure can be supplied from the brake cylinder pipe 45 tothe brake cylinders only by way of chamberM, passage 61, chamber 66,past the unseated ball check valve 65 of the inshot valve device 4|,passage 1S, chamber 49, passage 5|, chamber 52, and pipe 53.

The degree of brake cylinder pressure attained in the emergencyapplication of the brakes is, however, limited according to the pressuresetting of the inshot valve device 4|. As previously indicated, a brakecylinder pressure of, for example, twenty or thirty pounds per squareinch causes seating of the check valve $5. Thus, when the pressure ofthe fluid supplied to the brake cylinder I3 is suiiicent to causeseating oi the check valve E5, further supply of fluid under pressure tothe brake cylinder is cut off. It will thus be apparent that upon thefailure of the brake control circuit including the train wire I8 and thetrain wire I9, the signal lamp 26 is illuminated and an automaticemergency application of the brakes is effected.

In a similar manner, if the brake control circuit including the trainwires 2|] and 2| breaks or fails due to a ground or other fault thereonwhile the train is traveling along the road with the brakes released,the electromagnet 51 of the release magnet valve devices 39 and theelectromagnet s3 of the relay 25 are deenergized. As a result of theydeenergization of each release magnet valve device 39, each releasevalve 56 is unseated. As a result of the deenergization of the relay 25,the contact member 99 thereof is shifted to circuit-closing position tocause energization of the signal lamp 21 and the contact member II isshifted'to circuit-closing position to cause energization of theelectromagnet |01 of the magnet valve device 2S.

After a predetermined time interval, deter-` mined by the capacity ofthe volume reservoir 33 and the size of the port H2 of the magnet valvedevice 29, the pressure in chamber |23 of the application valve device3| is reduced and the application valve device 3| is operated toreducethe pressure in the brake pipe II at an emergency rate, as in the caseof breakage of or fault on the circuit including the wires I8 and I il.As in the previous instance, reduction of the pressure in the brake pipeII at an! emergency rate causes operation of the triple valve devicesI5, IEa and |511 to supply fluid under pressure from the auxiliaryreservoirs I6, Illa and Mb to the brake cylinders I3, |3c and |3b,respectively. In this instance, however, when brake cylinder pressure isbuilt up sufliciently and checkl valve i5 of the inshot valve device 4|is seated to cut oit the flow of iluid under pressure to the brakecylinder therepast, fluid under pressure continues to be suppliedA pastthe unseated cut-off valve 43.

Since, as previously indicated, the pressure setting of safety valve d2is a few pounds per square inch higher than the pressure setting of theinshot valve device di, the pressure in each brake cylinder will buildup to the pressure setting of the safety valve 42 and thereafter, uidunder pressure will escape to atmosphere past the safety valve.

It will be apparent that the signal lamps 26 and 21 selectively indicateto the operator which of the control circuits have failed and thus theoperator is advised, to some extent, as to the location of the failureor fault.

Whenever an automatic emergency application of the brakes is effecteddue to fault on or failure of the brake control circuit, the operatorimmediately slufts the handle 35 of the brake valve I2 from releaseposition to lap, service application, or emergency application positionin order to cut off the charging communication through the brake valvedevice I2 to the brake pipe This prevents the subsequent restoration ofbrake cylinder pressure to effect undesired automatic release of thebrakes.

In order to enable the train to proceed after the occurrence of a faulton or failure of any of the brake control circuits, the operator opensthe knife switch ii in the wirev I @3 leading to the electromagnet ofthe magnet valve device 29. The magnet valve device 29 is thusdeenergized regardless of the fact that the contact member lol of therelay 25 or contact member 91 of the relay 215 may be in circuit-closingposition. The valve |65 of the magnet valve device 29 is thus 1re-seatedso that when the operator subsequently restores the operating handle 35of the brake valve device I2 to release position, the consequentunseating of the diaphragm valve I 21 of the cut-off valve device 32,due to the reduction of brake cylinder pressure below the pressuresetting of the cut-oli valve device, will not result in anotherautomatic emergency application of the brakes. It will be observed,however, that either one or both of the signal lamps 26 and 21 remainilluminated to continually remind the operator of the faulty conditionof the brake control circuits. It is true that in the event of a fault,breakage or other failure of any of the brake control circuits, themaximum degree of brake cylinder pressure attainable is limitedthereafter either according to the pressure setting of the inshot valvedevice 11| or of the safety valve device di?. However, by proceeding ata reduced speed, such degree of brake application will be adequate toenable the vehicle or train to proceed to its destination or other pointwhere a better opportunity is presented for detecting and repairing thefault or failure in the control circuits.

In the event that a fault on or breakage of one of the train wires I8 to2| occurs during an application of the brakes when the brake cylinderpressure has already attained a degree suiiicient to cause closing orseating of the diaphragm valve |21 of the cut-off valve device 32, theenergization of the magnet valve device 29 due to deenergization ofeither one or both the relays 24 and 25 is ineffective to causeoperation of the application valve device 3| to eiTect an emergencyreduction in brake pipe pressure. Accordingly, the only result, in sucha case, is the illumination of one or both of the signal lamps 26 and 21and if it happens to be the control circuit for the release magnet valvedevices 39 which is interrupted by the fault or breakage of the trainwire, a reduction in brake cylinder pressure to the pressure setting ofthe safety valve ft2.

After the train is brought to a. complete stop and the operator shiftsthe handle 35 of the brake valve device I2 to the release position torelease the brakes, the reduction of brake cylinder pressure below thesetting of the cut-ofi valve device 32 causes unseating of thediaphragm, valve |21 and, consequently, because the valve |05 of themagnet valve device 29 remains unseatecl, the chamber |23 of theapplication valve device 3| is vented and an automatic emergencyapplication of the brakes is then effected as in` the manner previouslydescribed. In the same manner as pointed out previously, it is then`necessary for the operator to open the knife switch Ill to deenergizethe magnet valve device 29 in order to enable the train to proceedtoward its destination.

Embodiment shown in Fig. 3

The embodiment shown in Fig. 3 is identical with the embodiment shown inFig. 1 except that a pressure-responsive switch device is additionallyprovided for interrupting the circuit of the signal lamps 26 and 21whenever the brake cylinder pressure exceeds a certain uniform lowpressure, such as two or three pounds per square inch.

The pressure switch |5| is illustratively shown as comprising a casingcontaining a piston |52 winch has a stem |53 carrying in insulatedrelation thereon a pair of contact members |54 and |55. interposedbetween one face of the piston and the casing is a coil spring |56 whichis effective to urge the piston into contact with an annular stop |51 onthe casing when the pressure of the fluid in a chamber |58 at theopposite side of the piston is less than a certain uniform low pressure,such as two or 'three pounds per square inch. The chamber |58 isconstantly connected to the brake cylinder pipe 53 through a branch pipe|59.

When the piston |52 of the pressure-responsive switch |5| is inengagement with the annular stop |51 the contact members |54 and |55 arecorrespondingly positioned in circuit-closing position in series-circuitrelation with the signal lamps' 25 and 21, respectively.

When an application of the brakes is effected and the brake cylinderpressure acting in cham.- ber |53 on the piston |52 of the pressureswitch |5| shifts the piston |52 upwardly against the resistance of thespring |55, the contact members |55 and |55 are shifted tocircuit-opening position and thereby prevent the illumination of thesignal lamps 25 and 21 to indicate the operative condition Vof theretardation controller |1 as in the embodiment shown in Fig. l.

It will be apparent, however, that if a fault on or breakage of any ofthe brake control circuits occurs while the brakes are released, thesignal lamps 26 and 21 will be illuminated, as described in the case ofthe embodiment shown 'Y in Fig. l, and an automatic emergencyapplication of the brakes will be eiected.

By thus providing the pressure switch |5|, the signal lamps 26 and 21are unable to function to inmcate the operating condition, of theretardation controller and, therefore, the operator knows denitely thatthe illumination of either or both of the signal lamps 26 and 21 is dueto a fault on or breakage of the control circuits..

Embodiment shown in Fig. 4

The embodiment shown in Fig. 4 is identical in most respects to theembodiment shown in Fig. l and differs therefrom in certain respectswhich will be pointed out briey.

Instead of providing relays 25 and 25 having two Contact members, theembodiment shown in Fig. 4 includes relays 25o and 25a each having onlyone contact member, corresponding to contact members 56 and 99 of therelays 2li and 25, respectively. Also the cut-off valve device 32 isomitted and the pipe |25 leading from the volume reservoir 35 isconnected directly to the chamber 85 of the magnet valve device 29.

The equipment shown in Fig. 4 also includes certain devices not part ofthe equipment shovm, in Fig. l, these devices including an electricalrelay |65, a magnet valve device |62, a pressure switch device 63, aswitch device illustrated as a knife switch |64, and a rectifier |65preferably of the dry disc type.

The electromagnets of the relays 24a and 25a are connected inseries-circuit relation with, the electromagnets of the cut-off magnetvalve de.- vices 38 and the release magnet valve devices 59,respectively, as in the embodiment shownl in Fig. 1 and the contactmembers 86 and 99 of relays 25a and 25a are adapted, when` incircuitclosing position, to respectively complete the circuitsconnecting the signal lamps 2S and 21 to the battery 86 to eiectillumination thereof.

The relay |6| comprises an electromagnet 11| eiective when energized tocause shifting of a pair o1" contact members |12 and |13 from a normalcircuit-closing position to a circuit-opening position. The contactmember |12 of the relay |6| is effective, when in circuit-openingposition, to interrupt the circuit for the electromagnet of the relay24a and the electromagnet i6 of the cut-orf magnet Valve devices 38. TheContact member |13 of the relay |6| is effective, when incircuit-opening position to interrupt the circuit for energizing theelectromagnet of the relay 25e and the electromagnet 51 of the releasemagnet valve devices 39.

The magnet valve device |62 comprisesl a'casing having a chamber |16containing a double beat valve |15 which is shifted from an upper seatedposition to a lower seated position upon energization of anelectromagnet |11. When the electromagnet |11 is deenergized, the doublebeat valve |15 is shifted to its upper seated position by a yieldingcoil spring |18 and establishes communication, past the lower open Valveseat, between the chamber |16 and a chamber |19 to which the brakecylinder supply pipe 53 is constantly connected. When the double beatvalve |15 is in its lower seated position, it cuts orf the communicationbetween the chambers |16 and 15 and establishes communication past theopen upper seat thereof between the chamber |16 and a chamber |8| whichis constantly open to atmzosphere through an exhaust port |82.

The pressure switch device |63 comprises a casing containing a piston|88 which has a stem |85 carrying in insulated relation thereon acontact member |86. At one side of the piston |84 is a coil spring |81which is interposed between the piston and the casing in such mann-er asto yieldingly urge the piston in one direction into engagement with anannular stop |88 on the casing. At the opposite side of the piston |84to the spring |81 is a chamber |89 which is constantly connected to thechamber |16 of the magnet valve device |62 as by a pipe |96.

The spring |81 normally urges piston I8@ into engagement with theannular stop |88, in which position the contact member |86 iscorrespondingly in circuit-closing position. When the pressure of theuid supplied to the chamber |89 exceeds a uniform low pressure, such astwo or three pounds per square inch, the spring |81 is overcome and thecontact member |85 is shifted to circuit-opening position.

The knife switch |64 is normally in circuitclosing position and isoperative manually to a circuit-opening position. The switch device |65may be of any other suitable type such as a common snap switch.

The electromagnet 11| of the relay i, the electromagnet |11 of themagnet valve device |62 and the electromagnet lill of the magnet valvedevice 29 are connected in parallel relation between a common Wire |9|and the negative or grounded terminal of the battery 86. The pressureswitch H3 and the manually operated switch I Ell are connected in seriesrelation in a wire !92 which is connected at one end to the nongroundedterminal of the signal lamp 26 and at the other end to the wire i 9 I.The non-grounded terminal of the signal lamp 2l is connected by a wireE93 to the wire E92, the rectifier U55 being connected in the wire E93in such manner as to permit the iiow of current through wire IISS towardthe wire |22 and to prevent the flow of current through the wire 595i inthe opposite direction. The rectiiier IEE is provided in order toprevent the illumination of the signal lamp 2'! when the ccntact member9E of the relay 24a is shifted to circuit-closing position.

In operation, assuming that the operator has operated the brake valvedevice i2 to effect a service application of the brakes, iiuid underpressure supplied to the brake cylinder I3 through the supply pipe 53flows to the chamber H119 of the pressure switch it@ through chamber Il@of the magnet valve device i 62 past the lower open valve seat of thedouble beat valve I'I5, the chamber I l@ and pipe IQI, and causes thecontact member ESS to be shifted to circuit-opening position when thep-ressure in the brake cylinder exceeds a certain uniform low pressure,such as two or three pounds per square inch.

Subsequently when the contact member 82 on the pendulum 8i of theretardation controller Il disengages the contact finger 8l as the trainis retarded at a'rate of, for example, three miles per hour per second,the circuit for energizing the electromagnet of the relay 24a, and theelectromagnet 46 of the cut-off magnet valve device 38 is interruptedVso that the contact member 96 of the relay 24d shifts tocircuit-closing position to cause illumination of the signal lamp 26.Also, the deenergization of the cut-oil magnet valve device 33 causesseating of the cut-ofi valve 43 of the cut-off magnet valve device 33.`As previously pointed out, the rectier 65 prevents the iiow of currentthrough the signal lamp 2 at this time. Furthermore, in view of the factthat the contact member E66 of the pressure switch S53 is incircuit-opening position, the relay ISI, and the magnet valve devices 52and 29 remain deenergized.

Subsequently, as the contact member 32 of the retardation controller I?disengages the contact finger 8B, the electromagnet 57 of the releasemagnet valve devices 33 and the electromagnet of the relay 25ct` aredeenergized. As a result the release valve 56 of each of the magnetvalve mechanisms IS, Ita and io is unseated and, if the brake cylinderpressure exceeds the pressure setting of the safety valve 12, thepressure inthe brake cylinder is reduced thereto.

The shifting of the contact member 99 of the relay 25a tocircuit-closing position completes the circuit for energizing the signallamp 2l' and the signal lamp is accordingly illuminated.

Thus, as long as the brake control circuits including the train wires i5to 2! remain unbroken and without a fault thereon, the signal lamps 2tand 2'! function as in the embodiment shown in Fig. 1 to indicate theoperative condition of the retardation controller Il.

In the event that a fault on or break of one of the control circuitsoccurs while the train is traveling along the road with the brakesreleased, the corresponding relay 24d or 25a included in circuittherewith is deenergized. The deenergization of either of the relays 24aor 25a results in the energization of the electromagnet I'II of therelay I 6I, the electrcmagnet I'I'I of the magnet valve device IGZ andthe electromagnet I'l of the magnet valve device 29. It will be apparentthat this energizing circuit extends from the posi-a tive terminal ofthe battery 8S, in parallel through one or the other of the contactmembers 96 or 99 of relays 24a and 25a, respectively, to the wire I92,thence in series through the contact member Iii of the pressure switchIi3 and the switch H54, to the wire ISI and thereafter', in parallel,through the respective electromagnets of the relay IEI, of the magnetvalve device 62 and of the magnet valve device 29 to the negativeterminal of the battery Sii through the ground connection in the mannershown.

Upon energization of the electromagnet lll of the relay I 6I both of theContact members I'l2 and I I3 are shifted to circuit-opening positionand, consequently, the energizing circuit for each of the relays 26u`and 25a is interrupted. Thus, assuming that the relay 24a was at firstdeenergized, the pick-up of the relay ISI results in the deenergizationof the relay 25a. Conversely, if the relay 25a is first deenergized duetoi a fault or the break in the train wires, then the energization ofthe relay IBI results in the deenergization of the relay 24a. Thus, inany case, both of the signal lamps 26 and 2 become illuminated and thecircuit for energizing the el-ectromagnet of the cut-off magnet valvedevices 38 and the release magnet valve devices 39 are both interrupted.

chamber i8@ of the pressure switch it is conl nected to atmospherethrough the pipe lili, chamber ITE, past the open upper Valve seat ofthe double beat valve exhaust port I82. Thus the energization of themagnet valve device I52 insures that the pressure switch |63 will remainin circuit-closing position once a fault on or a break `lof the trainWires occurs.

Energization of the electromagnet I'l of the magnet valve device 29results in the timed reduction of the pressure in the chamber i255 ofthe application valve device SI in exactly the same manner as describedfor the embodiment shown in Fig. l. 'Ihus the application valve device3i is operated after a certain time interval to effect a reduction ofthe pressure in the brake pipe II at an emergency rate, and the triplevalve device I5 thereupon operates to supply fluid under pressure fromthe auxiliary reservoir I4 to the brake cylinder I3 in the mannerpreviously described for the embodiment shown in Fig. 1 past the inshotvalve device 4I of the magnet valve mechanism It. It Will be apparentthat since the double beat valve |15 of the magnet valve device ISZ isin its lower seated position, the brake cylinder pressure established isineffective to cause the contact member IBG of the pressure switch U53to be shifted to circuit-opening position.

When the pressure in the brake cylinder attains a pressure suiiicient tocause seating of the ball check valve 65 of the inshot valve device 4I,the supply of fluid under pressure to the brake H5, chamber IBI,andcylinder is cut off since the cut-o valve A3 of the magnet valvedevice 3i! is already seated.

As in the case of the equipment shown in Fig. l, the operator uponobserving the simultaneous illumination of the signal lamps 26 and 2land upon sensing the automatic emergency application of the brakes,shifts the handle of the brake valve device I2 out of release positioninto lap, service application position or emergency application positionto prevent the recharge of the brake pipe I l to release the brakes asWell as the continued exhaust of fluid under pressure, supplied torecharge the brake pipe, by way of the application valve device (il,volume reservoir 33, past the unseated valve |5 of the magnet valvedevice 29, and the exhaust port I I2 of the magnet valve device 29.

If, after the train has been brought to a complete stop by the automaticemergency application of the brakes in the manner just described, theoperator desires to release the brakes and proceed either afterrepairing the fault or broken train wire or without removing the faultor repairing the broken wire, he must rst open the switch E64. Upon theopening of the switch |64, the relay IBI, the magnet valve device |62and the magnet valve device 29 are all deenergized and thereby restoredto their normal condition. The deenergization of the magnet valve device62 causes the pressure of the fluid in the brake cylinder to be suppliedto the pressure switch |63 and shift the Contact member |86 thereof tocircuit-opening position.

The deenergization of the magnet valve device 29 causes the valve |85thereof to be reseated so that the operator may restore the brake valvedevice I2 to its normal brake release position in which communication isestablished for charging the brake pipe II. Since the exhaustcommunication through the port I I2 of the magnet valve device 29 fromthe chamber |23 of the application valve device 3| is now closed, thesupply of fluid under pressure to the brake pipe will not causeunseating of the valve piston llt of the application valve device 3| andthus the brake pipe I I will be restored to its normal pressure. Thetriple valve I5 is thus operated to restore the auxiliary reservoir I4to its normal pressure and to establish communication through whichfluid under pressure is exhausted from the brake cylinder to atmospherepast the ball check valve 65 of the inshot valve device III, whichresults in the release of the brakes.

Thereafter, the train may proceed at a reduced speed until such time asthe fault or break in the control circuit is removed or repaired, themaximum degree of brake cylinder pressure attainable, however, beinglimited according to the pressure at which the ball check valve 65 ofthe inshct valve device il seats.

It will be understood that the knife switch itil must remain in openposition if the operator desires to cause the train to proceed withoutimmediately removing the fault or repairing the break the controlcircuits, because otherwise upon the release of uid under pressure fromthe brake cylinder, the pressure switch |63 will reclose and theequipment will then be conditioned so that the automatic emergencyapplication of the brakes will be repeated. When the fault or the breakin the control circuits is removed or repaired, the knife switch |64 isreclosed to restore the retardation control circuits to their normalcondition shown in the drawings.

Summary summarizing, it will be seen that I have disclosed threeequipments embodying my invention, each of these equipments includingsignaling means for indicating a fault or break in the brake controlcircuits. In two of the embodiments the signal devices function in adual capacity, being effective when there is no fault or break in thebrake control circuits to indicate the operative condition of aretardation controller device as long as the degree of brake applicationestablished exceeds a certain uniform degree. In the remainingembodiment, a pressure switch responsive to brake cylinder pressure isprovided for preventing operation of the signal devices when the brakecylinder pressure exceeds a certain uniform low pressure, thusrestricting the function of the signal devices to indicating solely theoccurrence of a fault or break in the brake control circuits.

While I have disclosed only three embodiments of my invention, it willbe apparent that various omissions, additions or modicaticns may be madein the embodiments shown without departing from the spirit of myinvention. It is accordingly not my intention to limit the scope of myinvention except as it is necessitated by the scope of the prior art.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A vehicle brake system, comprising in combination a normally closedcircuit, electroresponsive means operating on said normally closedcircuit for controlling the degree of application of the brakes, aretardation controller operative upon the retardation of the vehicle tocause interruption of the said normally closed circuit and consequentoperation of the `electroresponsive means to control the -degree of theapplication of the brakes, means operative automatically uponinterruption of said normally closed circuit for effecting an emergencyapplication of the brakes, and means effective as long as theapplication of the brakes exceeds a certain uniform degree forpreventing operation of said emergency application means.

2. In a vehicle brake system, means manually operative to effect anapplication of the brakes, a normally closed circuit, electroresponsivemeans operating on said normally closed circuit for controlling thesupp-ly and rele-ase of fluid under pressure to control the degree ofthe application of the brakes independently of the manually operativemeans, a retardation controller effective upon the retardation of thevehicle in excess of a certain rate for eiecting interruption of thesaid normally closed circuit and the consequent operation of theelectroresponsive means to control the degree of the brake application,means operative automatically upon the interruption of said normallyclosed circuit for effecting an emergency application of the brakes, andmeans eiective as long as the brake application exceeds a certainuniform degree for preventing operation of the emergency applicationmeans.

3. In a vehicle brake system, a normally closed brake control circuit,signal means operated upon interruption of said normally closed circuit,means operative upon interruption of said normally closed circuit toeiect an emergency application of the brakes, and means eiective as longas the brake application exceeds a certain uniform degree for preventingoperation of the emergency application means upon interruption of thenormally closed circuit.

4. In a vehicle brake system, a normally closed brake control circuit, aretardation controller operative when the vehicle exceeds a certainuniform rate of retardation for interrupting said normally closedcircuit to control the degree of application of the brakes, signal meansoperated upon interruption of said normally closed circuit, meansoperative upon interruption of said normally closed circuit foreffecting an emergency application of the brakes, and means effective aslong as the brake application exceeds a. certain uniform degree forpreventing operation of the emergency application means.

5. In a vehicle brake system, means operative to cause fluid underpressure to be supplied through a communication to effect application ofthe brakes, a first normally closed circuit, a second normally closedcircuit, magnet valve means operating on said first circuit andoperative upon interruption of said rst circuit to close thecommunication through which uid under pressure is supplied to effectapplication of the brakes, a second magnet valve means operating on thesaid second circuit and effective upon interruption of the said secondcircuit to release fluid under pressure from said communication toeffect release of the brakes, a retardation controller operative uponthe retardation of the vehicle in excess of a certain uniform rate forinterrupting said first circuit and upon retardation of the vehicle at asecond certain uniform rate higher than the rst said uniform rate forinterrupting said second circuit, signal means operated uponinterruption of said iirst circuit, different signal means operated uponinterruption of said second circuit, means operated upon interruption ofeither of said circuits for eifecting an emergency application of thebrakes, and means effective as lon-g as the brake application exceeds acertain uniform degree for preventing operation of the emergencyapplication means.

6. In a vehicle brake system, a brake cylinder, means providing acommunication through which iiuid under pressure is supplied to thebrake cylinder to effect an application of the brakes, electroresponsivevalve means controlling the supply of fluid under pressure through saidcommunication to the brake cylinder and the release of iiuid underpressure from the brake cylinder through the said communication forcontrolling the degree of the application of the brakes, a normallyclosed circuit on which said electroresponsive means operates, aretardation controller operative upon retardation of the vehicle at arate in excess of a certain uniform rate for interrupting said circuit,signal means operated upon interruption of said normally closed circuit,means operated upon interruption of said normally closed circuit foreffecting a supply of fluid under pressure to the brakey cylinder toeffect an einergency application of the brakes, and means effective whenthe pressure in the brake cylinder exceeds a certain uniform pressurefor preventing said emergency application means from effecting anemergency application of the brakes.

7. A vehicle brake system comprising aY normally Vclosed brake controlcircuit, means operative upon failure of said brake control circuit foreffecting an emergency application of the brakes, and means effectivelas long as a brake application exceeding a certain uniform degree existsfor preventing the said emergency application means from effecting anemergency application of the brakes.

8. In a vehicle brake system, a normally closed brake control circuit,signal means operated upon failure of said circuit, and means effectiveas long as a brake application exceeding a certain uniform degree existsfor preventing the operation of the signal means.

9. In a vehicle bra-ke system, a normally closed brake control circuit,a retardation controller operative upon the retardation of the vehicleat a rate in excess of the certain u niform rate for interrupting saidcircuit, means operative upon failure of said circuit as long as thebrake application is less than a certain uniform degree for effecting anemergency application of the brakes, and means effective to delay for auniform interval of time the operation of the said emergency applicationmeans following the failure of the said circuit, to avoid undesiredoperation thereof upon accidental and undesired interruption of thecircuit by the retardation controller.

l0. In a vehicle brake system, a lnormally closed brake control circuit,electroresponsive means effective upon failure of the said circuit forcausing an emergency application of the brakes, and a pressure operatedswitch device effective to prevent operation of the electrorcsponsivemeans when the brake application exceeds a certain uniform degree.

l1. In a vehicle brake system, a normally closed brake control circuit,a normally open circuit, means operating on said normally closed brakecontrol circuit effective upon interruption of said normally closedcircuit for closing said normally open circuit, means operative upon theclosing of said normally open circuit for effecting an emergencyapplication of the brakes, and means effective to maintain the normallyopen circuit open as long as the brake application exceeds a certainuniform degree.

l2. In a vehicle brake system, a normally closed brake control circuit,a normally open circuit, means effective to close the normally opencircuit upon interruption of the normally closed brake control circuit,means operating on the normally open circuit and energized upon thecompletion of the normally open circuit for causing an emergencyapplication of the brakes to be eifected, a pressure operated switchdevice in said normally open circuit for maintaining the normally openYcircuit open as long as the brake application exceeds a certain uniformdegree.

13. In a vehicle brake system, a normally closed brake control circuit,a brake cylinder, means operating on said normally closed circuit forcontrolling the degree of pressure in the brake cylinder,electrorespcnsive means eifective when energized to cause fluid underpressure to be supplied to the brake cylinder to effect an emergencyapplication of the brakes, means operative upon the failure orinterruption of said normally closed brake circuit for causing the saidelectroresponsive means to be energized, a pressure operated switchdevice operated in response to a certain uniform pressure to preventenergization of tne said electroresponsive means, and a magnet valvedevice normally conditioned to establisii a communication through. whichthe pressure operated switch device is subjected to the pressure in thebrake cylinder and operated upon energization of the saidelectroresponsive means to cut on the communication between the brakecylinder and the pressure operated switch and il O release fluid underpressure from said pressure operated switch device to prevent operationthereof by the pressure in the brake cylinder upon an emergencyapplication of the brakes.

14. In a vehicle brake system, a no-rmally closed brake control circuit,a brake cylinder, means operating on said normally closed circuit forcontrolling the degree of pressure in the brake cylinder,electroresponsive means effective when energized to cause fluid underpressure to be supplied to the brake cylinder to eifect an emergencyapplication of the brakes, means operative upon the failure orinterruption of said normally closed brake circuit for causing the saidelectroresponsive means to be energized, a pressure operated switchdevice operated in response to a certain uniform pressure to preventenergization of the said electroresponsive means, and a magnet valvedevice normally conditioned to establish a communication through whichthe pressure operated switch device is subjected to the pressure in thebrake cylinder and operated upon energization of the saidelectroresponsive means to cut off the communication between the brakecylinder and the pressure operated switch and release uid under pressurefrom said pressure operated switch device, to prevent operation thereofby the pressure in the brake cylinder upon an emergency application ofthe brakes, and manually operative switch means operated at will toeffect deenergization of the electroresponsive means.

15. In a vehicle brake system, means providing a communication throughwhich fluid under pressure is supplied to effect an application of thebrakes, a cutoff magnet valve device operative to close saidcommunication, a release magnet valve device operative to release fluidunder pressure from said communication to reduce the degree ofapplication of the brakes, a normally closed circuit on which the saidcut-olf magnet valve operates, another normally closed circuit on whichthe said release magnet valve operates, and means operative uponinterruption of one or the other of said normally closed circuits foreiTecting interruption of both said circuits.

16. In a vehicle brake system, means providing a communication throughwhich fluid under pressure is supplied to effect an application of thebrakes, a cut-off magnet valve device operative to close saidcommunication, a release magnet Valve device operative to release fluidunder pressure from said communication to reduce the degree ofapplication of the brakes, a normally closed circuit on which the saidcut-off magnet Valve operates, another normally closed circuit on whichthe said release magnet valve operates, and means operative uponinterruption of one or the other of said normally closed circuits foreffecting interruption of both said circuits, and means effective whenthe brake application exceeds a certain uniform degree for rendering thelast said means non-effective.

ELLIS E. HEWITT.

